1. Field of the Invention
The present invention relates to a three-unit zoom lens system of a small size, and an image pickup apparatus such as a compact digital camera in which, the three-unit zoom lens system is used.
2. Description of the Related Art
In an image pickup apparatus such as a digital camera and a video camera, a high image quality and a high magnification have been sought. Whereas, taking into consideration a manufacturing cost, sometimes, lenses are formed by plastic, replacing glass.
For instance, in Japanese Patent Application Laid-open Publication No. 2006-220766, a three-unit zoom lens system which includes a first lens unit having a negative refracting power, a second lens unit having a positive refracting power and a third lens unit, and in which, a positive lens made of plastic is used nearest to an object, in the second lens unit has been disclosed. In this zoom lens system, a point of cost is taken into consideration while securing a zooming ratio of about 2.5.